Just a quick thought about what Iowa may or may not accomplish for the Dems. First, the three easy scenarios: 1.) Hillary wins by more than a point or two, in which case the race is basically over. 2.) Obama wins convincingly (five points or more), in which case it starts looking pretty good for him and Edwards is done. 3.) Edwards wins convincingly and Obama is third, in which case Obama is probably done and Hillary and Edwards duke it out (with Hillary enjoying a near-prohibitive financial advantage).
Short of one of these things happening, I think we're looking at the muddle Mike was talking about last weekend. But here's the thing: An inconclusive muddle actually benefits Obama. The reason is that a muddle kills Edwards, who needs the kind of fundraising and free-media boomlet that only a clean victory can provide. And without Edwards in the race, Obama consolidates the anti-Hillary vote, which nudges him over the top in what's now a dead-even race in New Hampshire, makes things look pretty good for him in South Carolina (where he's been closing but still has to convince some African-Americans he can win), and generally gives him the upper hand for the nomination.
So, somewhat counter-intuitively, Obama may have at least as many if not more "paths" to the nomination as Hillary, which is worth keeping in mind.